The purpose of the tibial plateau leveling osteotomy (TPLO) procedure is to stabilize the cranial cruciate ligament (CCL)—deficient canine stifle by reducing the tibial plateau slope thereby neutralizing the cranial tibial thrust force or redirecting it into a caudal direction. See, for example, Kowaleski, et al. “The Effect of Tibial Plateau Leveling Osteotomy Position on Cranial Tibial Subluxation: An In Vitro Study, Veterinary Surgery, 34:332-336 (2005), incorporated herein by this reference. A segment of the upper tibia is cut and rotated and then rejoined to the lower portion of the tibia using a bone plate. See, for example, U.S. Pat. No. 8,523,921 incorporated herein by this reference.
Most bone plates are designed for specific procedures and/or bones. There are numerous examples. See, for example, U.S. Pat. No. 6,096,040 (designed for the proximal humerus). There are also numerous patents for various bone plate screw hole designs and other aspects of bone plates.
Further, there are several bone plate designs specifically for use in TPLO procedures. See, for example, U.S. Pat. Nos. 5,304,180; 7,740,648 (and D536,453); U.S. Pat. No. 8,177,818 (by the assignee hereof); U.S. Pat. No. 8,523,921; and U.S. Patent Application Publication No. 2006/0149275 all incorporated herein by this reference.
In some TPLO procedures, the cut is made fairly high on the upper tibia with reported benefits as opposed to the case where a large portion of the upper tibia is cut and rotated. During some TPLO procedures, including when the cut is made higher and due to the rotated tibia segment, some prior TPLO plates require that the lower leg section of the plate be angled with respect to the lower tibia. Sometimes, the head section of the TPLO plate is not tailored or optimized for the now smaller rotated cut upper tibia segment. The result could be a TPLO procedure where the TPLO plate has to be bent and/or shaped for each animal. The surgery time is thus increased when inter-operative bending of the TPLO plate is required. The result can also be bone plates which do not properly secure the two tibia sections together, bone screws which do not properly hold (shorter bone screws may have to be used) and/or which extend into the stifle (knee) joint causing damage to the articular and periarticular surfaces possibly leading to osteoarthritis. Other TPLO plates have a head shape which interfere with features of the cut, rotated tibial plateau.